1. Field of the Invention
The present invention relates to a combustor of gas turbine for a thermal power plant and the like.
2. Description of the Prior Art
FIG. 2 is an explanatory view of a prior art premixed flame low NO.sub.x type combustor of gas turbine for a thermal power plant and the like. In this figure, the gas turbine combustor has therein a combustor 203 of cylinder body and eight pieces of main burners 201 are disposed in the combustor 203 around central axis thereof. Main fuel supplied from main fuel nozzles and combustion air are mixed to form a pre-mixture, which is burned in the combustor 203 with a pilot of a pilot fuel supplied from a pilot fuel nozzle 202. The combustion air flows on an outer periphery of the combustor 203 and turns 180.degree. at an air inflow portion 205 to enter the combustor 203. In FIG. 2, numeral 204 designates a pilot air swirler, which is disposed for supplying combustion air for burning the pilot fuel.
In the prior art gas turbine combustor as mentioned above, the combustion air flows on the outer periphery of the combustor 203 of cylinder body and then turns 180.degree. at the air inflow portion 205 to enter the combustor 203, hence the combustion air, so turned, is biased to the central portion, so that velocity distribution of the combustion air in the combustor 203 in the cross section A--A of FIG. 2(a) tends to become faster at the central portion of the combustor 203 and slower at the peripheral portion of same.
If such biasing occurs in the velocity distribution of the combustion air in the combustor 203, concentration of the premixed fuel of the main fuel and the combustion air becomes non-uniform and there arise shortcomings such that NO.sub.x generating at the main burners 201 in the combustion becomes high in concentration, combustion range for effecting a stable combustion in the combustor 203 becomes narrow, etc.